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A Diet Manifesto: Drop the Apple and Walk Away

Another year ends, and still the war drags on. In the final salvo of 2010, the combatants are lobbing fruit.

Not literally, of course, though they might like to: The long war of the weight-loss diets has aroused passions just about as overheated as those of any military conflict.

How is a person best advised to lose extra weight and retreat from diabetes and heart disease? Count calories, cut fat and fill up on fruits and vegetables? Or turn instead to a high-protein, high-fat regimen like the one popularized by Dr. Robert C. Atkins?

The experts point vehemently in all directions. And so in one corner this month we find the chief executive of Weight Watchers — one of the calorie-driven, “balanced diet” options — gleefully announcing on the radio that he was giving out fruit baskets for Christmas in honor of his organization’s new “Plus Points” program, in which fruit can be freely eaten.

In the opposite corner we have Gary Taubes, the science journalist who has thrown in his lot with the high-fat, high-protein crowd, arguing in his new book that the overweight should just put down their apples and walk away: “If we’re predisposed to put on fat, it’s a good bet that most fruit will make the problem worse, not better.”

At this point all eaters, fat or lean, could be forgiven for slamming the door on all expert dietary input, forever. But those who are curious about the science behind it all could do worse than to pick up Mr. Taubes’s book “Why We Get Fat: And What to Do About It.”

A few things to understand at the outset: First, despite the happy fact that unlike many in this field, Mr. Taubes is not out to sell you anything (other than his book), it is still a manifesto. Thus, though it is bursting with data, a reader has no way of knowing whether other data has been overlooked or minimized to support the author’s points.

Second, the new book is not really a new book at all; it is a sort of CliffsNotes version of “Good Calories, Bad Calories,” a long, dense tome Mr. Taubes published in 2007. With the new, smaller and more focused version, Mr. Taubes openly admits he is aiming for a broader audience and bigger impact. Fair enough, although one does begin to wonder if a line of protein bars is not far behind.

But all that aside, Mr. Taubes proceeds to stand the received wisdom about diet and exercise on its head in a particularly intriguing and readable synthesis.

We’ve got the whole thing backward, he argues. The overweight are not lazy hogs who eat too much and exercise too little. The thin are not virtuous and disciplined. Rather, all of us are fulfilling a fixed biological mandate, just as growing children are. Our bodies have a nonnegotiable agenda, and our behavior evolves to make that agenda happen, he writes: “Eating in moderation and being physically active (literally, having the energy to exercise) are not evidence of moral rectitude. Rather, they’re the metabolic benefits of a body that’s programmed to remain lean.”

In other words, you don’t haul your body off that couch and out to the gym; your body hauls you.

Meanwhile, “those who get fat do so because of the way their fat happens to be regulated,” Mr. Taubes writes. “A conspicuous consequence of this regulation is to cause the eating behavior (gluttony) and the physical inactivity (sloth) that we so readily assume are the actual causes.”

The actual causes, he argues, with a great deal of observational and experimental data to support his points, are the array of regulatory enzymes and hormones that move fuel, in the form of fat and sugar molecules, in and out of storage depots around the body.

And the only one of these hormones under even a smidgen of voluntary control is insulin. At this point Mr. Taubes merges onto the narrative highway traveled by all low-carb advocates: The body’s insulin levels are largely determined by ingested carbohydrates, and for some people the high-carb foods that stimulate insulin secretion and cravings for more high-carb foods are, in this worldview, just so much poison.

So that apple — a filling package of fiber and vitamins to the Weight Watchers folks — is just a serving of fructose to Mr. Taubes. Fructose is the problematic sugar our bodies turn to fat the most readily, and if you are programmed to be fat, an apple will make you that much fatter.

Mr. Taubes draws an analogy to cigarette smoking: Not every long-term smoker gets lung cancer — in fact, only a minority do — but among people with lung cancer, smoking is by far the most common cause. “In a world without cigarettes, lung cancer would be a rare disease, as it once was,” he writes. “In a world without carbohydrate-rich diets, obesity would be a rare condition as well.”

How to account for the fact that in virtually all head-to-head comparisons of various diet plans, the average long-term results have invariably been quite similar — mediocre all around? The party line holds that backsliding is universal. Mr. Taubes makes much of the addictive effect of carbohydrates: once you taste them you never forget them.

But those studies report group outcomes. Every plan has its own rare, shining success stories as well. Sometime, a diet just clicks.

Perhaps the remarkable diversity of the human organism — whose various sizes and shapes (double chins, giant thighs and all) are so clearly driven by such a vast array of different appetites and genetic cues — simply means that it is foolish to expect a single diet to serve all comers.

There. A proposal to end the war, just in time for the new year.

A version of this review appears in print on December 28, 2010, on page D6 of the New York edition with the headline: A Diet Manifesto: Drop the Apple and Walk Away. Order Reprints|Today's Paper|Subscribe